A transistor device (a MOSFET, a JFET, a MESFET, an IGBT, etc.) is a three-terminal device for transmitting a current through a control of a gate terminal, particularly a power semiconductor transistor for a switching is required with a high breakdown voltage and a large current.
The transistor device has different electric characteristics depending on the structure, and an appropriate device is used depending on an application field. However, a high current density, a low turn-on voltage, a high breakdown voltage, a low leakage current, a fast switch speed are commonly required, and In order to simultaneously satisfy the above requirements, various structures have been proposed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.